Temperature controlling system



March l. E. MccABE 2,233,674

TEIPERATURE CONTROLLING SYS-TEI Filed Aug. 3, 19:58 2 Sheets- Sheet 1 INVENTOR. pm E. MCL'HEE BYWM ' ATTORNEY.

March 4, 1941. I. E. McCABE TEMPERATURE coumonune-s swsu FiIed'Aug. 5, 1938 2 Sheets-Sheet 2 fmd I N V EN TOR. pm E. M C/75E A TTORNEY Patented Mar. 4, 1941 UNITED PATENT OFFICE Claims.

Thisinvention relates to an improved system for controlling the temperature within a building employing an electrically operated and controlled heating plant and more particularly to such a system which responds to sudden and decided changes in temperature exterior of the building and anticipates the resulting demands upon the heating plant to maintain an even temperature within the building.

Thermostats have long been used' for controlling the operation of automatically controlled heating plants for the purpose of establishing a desired temperature in a space to be heated. These devices operate on a differential in tem-.- perature, which may be one degree, to call for an operation of the heating plant upon a drop in the temperature of the space to be heated and to stop said operation when the temperature of the space has risen an amount equal to the operating differential oi the thermostat.

With these conventional types of thermostats it ha been possible, when constructed to be very sensitive to" temperature changes, to open and close a circuit upon a change of one degree tem-' perature at the thermostat.- It has also been possible to maintain the temperature oi' the space substantially at the setting of the thermostat, when a temperature diflerential exists between the space to be heated and a space exterior therefrom, such as the outdoors, providing the exterior tempe ature difference is established by a slow change temperature or remains substantially around a certain degree. The conventional types of thermostats have proven inadequate when quick or drastic changes in exterior temperature occur, whether they be toward higher or lower temperatures, to prevent such changes from resulting in an over or under temperature condition in the space to be heated. This can be attributed to a delay in modifying the eflect or such exterior temperatures upon the interior space, whereby, when thethermostat does flnally operate, either to stop or start the heating plant, the effect of a rising exterior temperature when the plant is operating may produce an overtemperature condition in the space, and when the exterior temperature is falling, the lag in the heating plant in responding to produce the demand made by the thermostat produces an undertemperature condition.

With the best of thermostatic control operation it is natural for the space temperature to decline somewhat after influencing the thermostat to start the heating plant, due to the time required of the plant to produce heat and'a slight inis a vapor pressure actuated element having a crease in space temperature is to be expected after the thermostat demand has been met, due

to the continued heating effect of the high temperatures produced at the heating source. While these variations may be slight-say, only one degree, and not ordinarily influencing the state of temperature comfort within the space to be heated, they may materially contribute'to a state of discomfort, should drastic changes in exterior conditions occur.

A device for accomplishing the same general objectives as this improved system is disclosed in this applicant's prior co-pending application, Serial No. 221,645, flied July 27, 1938. In said application the single device includes a room thermostat responsive to changes in temperature within the building in combination with a Bourdon tube responsive to changes in temperature exterior of the building so arranged that sudden changes in tempe ature exterior the building. varied the normal response of the room thermostat to ambient temperature to anticipate the demand upon the heating plant resulting from sudden changes in temperature exterior of the building.

It is an object of this invention to provide a system of thermostatic control employing at least two thermostats one located within a space to be heated, such as a building, and the other located exterior of said space, such as the outdoors, said thermostat being electrically connected in the system so that the exterior thermostat in responding toreversals in temperature influences the temperature requirements of the thermostat located within the space to be heated whereby control of the heating plant by the interior thermostat located within the space to be heated will produce the same results, as disclosed above, by the-single device of the applicants co-pending application. 40

This system offers an advantage over the meth- 0d of control accomplished by the single device of the co-pending application. In the single de-- vice, one of thetemperatureresponsive means bulb, containing the thermal liquid, subjected to the temperature exterior of the building thus making it expedient to locate the device where the connecting tubing between the bulb and element may be as short ,as possible both from the standpoint of installation as well as appearance. In this improved method of control, each of the temperature responsive devicesmay be independent units, each operating their respective switches in the control circuit and thus may each be 10- cated at points deemed best suitable for their operation, accessibility to adjustment, appearance and installation in the system.

With these and other objects in view reference i made to the accompanying sheets of drawing illustrating a preferred form of this invention with the understanding that detail changes may be made without departing from the scope thereof.

In the drawings:

Figure 1 is a schematic view of an application of this improved system of controlling an electrically operated and controlled fluid fuel burning heating plant shown in diagram as located in a building together with a thermostat shown in diagram located within the same building and a cooperating thermostat shown in diagram lo cated upon the exterior of said building, and a wiring diagram of the electrical connections of the two thermostats to each other and to the electrical controls of the heating plant.

Figure 2 is an enlarged detail view in section of the thermostat located within the building, taken on the line 2-2, Figure-3, looking in the direction of the arrows.

Figure 3 is a similar view taken on the line 2-3, Figure 2, looking in the direction of the arrows.

Figure 4 is an enlarged detail view in front elevation of the thermostat located upon the exterior of the building.

Figure 5 is a fragmentary, enlarged detail view in perspective of the outer magnetically operated mercury tube switch shown in Figures 2 and 3 and the magnetic operator therefor;

In the embodiment of this invention, illustrated in Figure 1, a commercial boiler or furnace A for the heating plant is shown located below the floor B of a building having a side wall C. A commercial electrically operated and controlled fluid fuel burner D is shown installed in connection with the boiler of furnace A. The electric current is shown passing through the wires L and L from the source of commercial current through a hand switch HS and through a commercial boiler control BC to a control panel C? of commercial construction.

The control panel mounts various switches and binding posts for connecting the line current to the motor M and ignition transformer and includes transformer means for the secondary circult to the thermostats T and I as disclosed in this applicant's. prior Patent No. 2,024,697, granted December 17, 1935.

The thermostat 'I' is shown in detail in Figures 2 and 3. This instrument includes two magnetically operated mercury tube switches I and 2, preferably of the type disclosed in Patent No. 2,085,316, granted June 29, 1937, and is prefer- I ably mounted on the wall of the building in the room wherein a certain predetermined temperature is desired to be maintained and is responsive to changes in ambient temperature.

,The thermostat '1 is shown in detail in Fisure 4 oi the drawings. This instrument includes a single magnetically operated mercury tube switch 2 of the same type as the switches I and 2 and is preferably on the outside of a wall of the building and is responsive to changes in temperature upon the exterior of the building.

As shown in Figures 2 and 3, the mercury tube I of thermostat '1' is mounted in a bracket clip 4 extending outward from a base 5 which bracket also mounts the mercury tube switch 2 parallel to tube I intermediate between tube I and the base 5.

As shown in detail in Figure 5, the mercury tube switch I includes an armature 5 mounted upon one of the electrodes of the switch, which in this case is normally in the open position. A magnet 'I is mounted on the free outer end of a thermostatic coil 2, the inner end of which is mounted on a bracket 9 rotatably carried on the end of a. post I0 mounted upon the base 5. As the thermostatic coil 8 responds to changes in ambient temperature the magnet I will be caused to approach or depart from the tube I. The armature 5 will be influenced by the magnet when adjacent to the exterior of the tube I to close the circuit through the switch and when the magnet is moved to carry its magnetic field away from the tube I sufficiently to free the armature, the switch I will open. The magnet I is preferably carried on a plate II with its lower end secured to the free outer end of the coil I. The plate II extends beyond the upper side of the magnet 1 and is provided'with an elongated slot I2 for the reception ofa screw threaded member I3 having an enlarged head II on the side adjacent the tube I. The screw threaded member I3 is adjustably received in a bracket IS whereby the approach of the magnet I to the exterior of the tube I may be adjusted. The end of the post III also mounts one end of an adjusting lever I6, the other end oi which is adapted to travel over a calibrated temperature scale I1 supported by brackets ll upon the base 5. The end of the lever I6 mounted upon the post III is adjustably secured to the bracket 9 mountin the inner end of the coil 8 by an adjusting screw and washer I! mounted upon an extension 20 from the bracket 9, whereby the coil 8 may be calibrated to open and close the switch at a predetermined temperature.

The second mercury tube switch 2 carried on the base 5 by the clip bracket 4 is opened and closed by a magnet 2I carried upon the upper free end of a metalstrip 22, the lower end of which is pivotally mounted upon a stud 22 upon the base 5. The magnet 2| is mounted upon a plate 2!, similar to the plate II mounting the magnet I, and is provided with a similar elongated slot.

ed member 25, similar to the adjustable screw threaded member I2, which is adJustably mounted in a bracket 26. As shown in Figure 2, the brackets I5 and 2B mounting the screw threaded adjusting members I3 and 25 are preferably mounted upon one of the brackets II. The adjustable screw threaded member 25 in the second switch terminates in an enlarged head 21, similar to the head I4 on the other adjusting member I3, and in addition thereto is provided with an annular flange 28 of similar size as the head 21- to extend over the outer side of the plate II secured to the outer end of the coil 8 and is provided with an adjusting screw 20 to engage said plate, so that as the temperature rises and causes The travel oi. the magnet 2| toward 'and from the tube 2 is limited by a screw threadsee ers the switch I to open and upon continued movement of the coil t in that direction the engage ment of the plate ll with the arm 29 will thereafter cause the strip 22 to rotate about its pivot 23 to move the magnet it away from the tube 2 and cause the switch '2 to open. The adjusting members it, 25 and 30 are so adjusted that upon changes in ambient temperature the switch 2 is closed before the switch i and the switch l is opened before the switch 2.

As shown in Figure i, in the thermostat T the switch tube ii is mounted in a bracket clip 3i extending outwardly from the base 32. A magnet 33 is carried upon a plate 35 secured to the outer free end of a thermostatic coil iii, to operate the switch a? in the same manner as the switch 3, except in this thermostat T the screw threaded adjusting member 36 mounted in the bracket 37? upon the base 32 is provided with two spaced apart stops in the form of an enlarged head 38 and an annular flange similar to the screw threaded adjusting member of switch oi thermostat T The inner end of the thermal coil 35 is secured to a bracket similar to the bra/cket 9 rotatably mounted on a post, not shown, supported upon the base 532 and is provided with extensions Mi, similar to the extension it on the bracket 9 shown in Figure 3. In place of an adjusting lever a friction washer ll is mounted on the end of the post having an adjusting screw 62 threaded axially in the end of the post. The free movement off-the plate it between the stops and which will still operate the switch is the minimum, operating differential which may be increased by turning the screw threaded adjusting member to to advance the stops in the direction of the tube Further movement of the coil in response to temperature changes in the same direction after the magnet carrying plate has engaged either one of the stops 38 or imparts a movement to the bracket connected to the inner end of the coil again% the friction of the washer 23. In other words, in this thermostat T an override means is provided atter a change in temperature has opened or closed the switch.

In carrying out this invention the switches in thermostat I may be adjusted so that movement of the bi-rnetal member 13, in'response to falling temperatures will first allow the rear switch 2 to close, wherearter, upon the continued falling of the temperature the front switch 6 is closed, and will therefore in the case of rise in term. pera-ture first open the front switch and then thereafter open the rear switch. 3ihe rear switch may, for example, close at 71 and open at 72 and the front switch may, for example, close at 76 open at 71. The thermostat T be adjusted so that the operating differential is 5,

which event the switch willmaintain an open circuit on rising temperature after an initial increase of 5 and will maintain a closed circult on a falling temperature after an initial decrease of 5.

This invention contemplates connecting the switches l, 2 and as shown in the wiring diagram in Figure l. The electrodes or switch Ii are connected by wires t2 and $3 in the secondary circuit of the control panel OP which circuit normally controls the operation of the burner D. One electrode of the switch 3 is connected. by wire it to wire 52 in the secondary circuit and the other electrode in the switch 3 by wire to one electrode of the switch 2 and the other electrode of the switch 2 is connected to, the wire it of the secondary circuit. it is therefore seen if switch 3 of the thermostat T is open, as in the case of rising outdoor temperature, the cir cult is also open through the high temperature switch 2 of the thermostat T and in no way affects the operation of the burner and therefore during a period of rising outdoor temperature the low temperature switch i of the thermostat T controls the operation of the burner. Upon a drop in outdoor temperature suflicient to close the switch 3 then switch 2 controls the operation of the burner. Switch 3 again takes charge of operating the burner when the outdoor temper-. ,atures again change to one of a rising temperature. V

The two stage operation of the thermostat T may be accomplished through the use of two independent thermostats, or pressure responsive devices may be substituted for the thermostats which devices are responsive, for example, to boiler steam pressures, with each device set for one stage of control operation and connected in the control system, with the thermostat exterior of the building to provide the system of the control disclosed by this invention and be the .full equivalent thereof.

This invention therefore provides a system of temperature control in which a reverse in temperature at one source will influence the demands made by a thermostatic device or devices located in a space in which an even temperature is de sired to be maintained, so that the effect which the temperature at one source may have upon the space to be heated is anticipated and cornpensated for by raising or lowering the demands of the said space rather than permi-ttingthe eiiects or such changes actually influencing the said space before thermostatic operation occurs, whereby substantially constant temperatures are made possible within the said space and eve heating and under-heating conditions are eliminated or minimized regardless of the state or" the temperature condition exterior the space to be heated.

This system may be used b0 control cooling apparatus as well as heating apparatus or systems.

it is to be understood that in adapting the heating system described herein to a cooling sys tem that certain changes may be necessary in the two stage thermostat, such as, constructing the coil of bi-rnetallic metal to respond to temperature changes to cause a reversal of the direction of movement oi the free end thereof. Likewise, it may be desirable to cause one switch to be closed by the magnet while the other switch be caused to open by the magnet. Under some cir cumstances or conditions, it may be desirable to open one circuit while the other is closed by this two stage thermostat. It is also to be understood that this two stage thermostat may be employed in other applications which may require the above changes details above described.

What claim is:

l. in a system for controlling the operation of an electrically operated and controlled heating plant, a twe -stage thermostat including two magnetically operated mercury tube switches, one switch connected in one control circuit and the other switch connected in another control cir= cult, a coil of iii-metallic metal responsive to changes in temperature to expand and contract, the inner end of said coil attached to an adjustable member and the free end of the coil mount ing a magnet to operate oneofsaid switches, a strip adjacent the free end of the, coil pivotally mounted at one end supporting on its free end a magnet to operate the other switch, an arm upon said strip extending into the path of movement ,0! the free end of the coil arranged to be engaged of said strip is so located that the weight of the magnet upon the free end of the strip will cause the arm of the strip to follow in contact with the movement of the tree arm of the coil.

3. The structure of claim 1, wherein the pivot of said strip is so located that the weight of the magnet upon the free end of the strip will cause the arm or the strip to follow in contact with the movement of the free end of the coil, and a stop for the free end of the strip to prevent it passing over the center of its pivot.

4. A two stage thermostat, including two switches, acontractible and expansible member responsive to temperature changes to operate one of said switches at a predetermined stage in temperature change and means actuated by the movement of the contractible and expansible member ata second stage in said temperature change to operate the other switch, said means provided with adjustable means for adjusting the relative stages of operation of said switches wherein said switches are magnetically operated mercury tube switches rigidly supported upon a base, wherein the contractible and expansible member is a coil of bi-metallic metal supporting a magnet upon the tree end to actuate the first stage switch, and wherein the means to operate the second stage switch includes a strip pivotally mounted at one end upon the base, and mounting a magnet on its free end adapted to operate the second switch, means limiting the movement of the free end of said strip and means carried upon said strip mounting an adjustable abutment extending in the path of the lmovement or the said contractible and expansible member.

5. A two stage thermostat, including two magnetically operated mercury tube switches, a coil of bi-metallic metal responsive to changes in temperature to expand and contract, the inner end of said coil attached to an adjustable member and the free end of the coil mounting a magnet to operate one of said switches, pivotally mounted means supporting a second magnet arranged to operate the other switch, means limiting the movement of the pivoted means and additional means mounted upon said pivoted means having an. abutment arranged to be engaged by, and to follow the movement of, the free end 0! the bimetallic coil, said abutment being adjustable to permit the switch responsive to the second magnet to be closed prior to and opened subsequent to, the closing and opening, respectively, of the other switch.

IRA E. MCCABE. 

